Traction control systems attempt to optimize vehicle acceleration and handling performance under low road/tire interface friction levels by controlling the slip of the driven wheels through wheel torque management via powertrain torque and possibly brake torque control. The friction forces acting at the driven wheel road/tire interfaces depend largely on the normal forces acting on these wheels. Estimating the normal forces and accounting for them in the control system can improve overall system performance.
During a traction control event as the load transfers from side to side, or front to rear during dynamic maneuvers, increasing normal loads requires increasing drive axle torque. Prior systems cause undershoots or insufficient driven wheel slip to fully utilize the available surface friction. Decreasing normal loads, on the other hand, leads to wheel speed flares because the inside wheels cannot support the torque.
It would therefore be desirable to adjust the traction control system to take into consideration load transfer to prevent undershoots or flares.